1. Field of Invention
The present invention relates to invention molding machines and more specifically to a rotary injection molding apparatus and method for its use.
2. Background of the Related Art
Injection molding machines are commonly used in the manufacturing industry for molding elastomeric materials such as rubber, plastic or combinations of these materials. For example, current vibration control components for the automotive industry are produced using large injection press machinery with multi-cavity molds. Multi-cavity molds produce large amounts of natural rubber waste from the large runner-system, cavity flash, and damaged cavities. The time and cost to engineer and manufacture these intricate molds and their associated tooling is very high. Product quality and consistency is also compromised due to the variation in cavity pressures and temperature.
The multi-cavity mold style of molding also requires extensive operator intervention, which can lead to operator error and operator injuries due to the hazards associated with the large, heavy, hot molds. Automating high-cavity molds is clumsy, expensive and often unsuccessful. The multi-cavity systems almost always require secondary finishing operations, which cost the plant time and money.
Additionally, in prior art multi-cavity mold systems, performing tasks such as mold changes for different parts required the use of heavy lifting equipment. Also, moving the press to another location is not easily done since many of these large presses require a large floor pit.
Prior examples of injection molding machine solutions which avoid the use of multi-cavity molds are disclosed in U.S. Pat. Nos. 6,604,936 and 5,843,487. The components of prior single mold injection molding systems typically include a stock supply assembly, an extruder assembly, an injection assembly, a mold and a clamping assembly. In a typical molding process, the stock supply assembly supplies a certain amount of stock material to the extruder assembly. The extruder assembly processes or plasticizes the stock material into injection material, and conveys the desired amount of material to the injection assembly. Upon clamping of the mold within the clamping assembly under the force necessary for successful molding, the injection assembly injects the injection material into a mold cavity within the mold. When a metal insert or other mold component is required in the molding procedure using an injection molding machine, sections or portions of the mold must initially be separated and an unfinished component, insert or work piece loaded into one of the mold sections. The mold sections are then assembled to form the internal mold cavity.
Once the mold cavity is formed, the mold is clamped under the necessary force to hold the unfinished inserts, components or work pieces in position during operation of the injection assembly, which injects the elastomeric molding material into the mold cavity. The mold sections are then opened or removed and the molded product having the previously unfinished, now molded part and insert or joined work pieces, are unloaded from the mold cavity. However, none of these prior solutions provides the advantages of a rotary injection molding system.